Table 1.

Characteristics of E2 assays used in large epidemiologic studies of bone health in postmenopausal women

StudyAssay methodE2 detection limit (pg/mL)*Lowest E2 tertile or quartile (pg/mL)*
Cummings et al., 1998 (1)Extraction/chromatographic RIA†5<5 (quartile)
Ettinger et al., 1998 (2)
Garnero et al., 2000 (3)Extraction/RIA‡3<11 (quartile)
Goderie-Plomp et al., 2004 (4)Direct immunoassay§1.3<11 (tertile)
Rapuri et al., 2004 (5)Direct immunoassay§2.27.1 ± 0.14 (tertile)∥
Ettinger et al., 2004 (6)Direct immunoassay1.4<2.7 (quartile)

  • ↵* Multiply pg/mL by 3.67 to convert to pmol/L.

  • ↵† Endocrine Sciences, Inc.

  • ↵‡ In-house method.

  • ↵§ Diagnostic Systems Laboratories.

  • ↵∥ Mean ± SD of lowest tertile.

  • ↵ Diagnostic Products Corporation.